1. Department of Economics, University of Bath, Bath BA2 7AY, UK
2. Istituto dei Sistemi Complessi (ISC)-CNR, 00185 Rome, Italy
3. Department of Mathematical Sciences, University of Bath, Bath BA2 7AY, UK
4. International Finance Corporation, World Bank Group, 20433 Washington DC, USA
5. Université Côte d'Azur, CNRS, GREDEG, 06560 Valbonne, France
6. Department of Social Policy and Sciences, University of Bath, Bath BA2 7AY, UK